Intel Layout Checklist (version 1.0)

Transcription

1 Intel Layout Checklist (version 1.0) Project Name Fab Revision Date Designer Intel Contact SECTION CHECK ITEMS REMARKS DONE General Obtain the most recent documentation and specification updates Documents are subject to frequent change COMMENTS Route the GLCI and MDI differential traces before routing the digital traces Place the at least 1 inch from the edge of the board. Layout of differential traces is critical. Refer to the design guide for detailed routing requirements. With closer spacing, fields can follow the surface of the magnetics module or wrap past edge of board. EMI may increase. Optimum location is approximately 1 inch behind the magnetics module. Place the RBIAS compensation resistor less than 1 inch from the Place the KBIAS compensation resistor less than 1 inch from the Place the JKCLK series resistor within 2 inches of the Route the JKCLK clock as a 50 Ω single-ended impedance (± 20%). Keep JKCLK at least 7 mils or more away from other traces. Clock Source Place crystal and load capacitors less than 0.75 inches from the Keep crystal lines 15 mils away from other signals. Keep crystal traces 6 mils in width. LCI Interface Design traces for 50 Ω single impedance (± 20%). The 33 Ω series resistor is required for signal integrity. Controlled impedance is required to reduce ringing and improve signal quality at the ICH. Keep 7 mil spacing to digital traces, I/O ports, and board edge. More spacing might be required to other high speed traces or clocks. This reduces EMI. This includes spacing to other digital traces, I/O ports, board edge, transformers, and differential pairs. 6 mils is best for low capacitance, which is important for crystal circuit frequency accuracy. Check trace impedance with an impedance calculator. Traces are 4 mils wide with 5 mils separation for designs with a dielectric thickness of 2.8 mils (nominal). 1

2 LCI Interface JTXD[2:0] and JRXD[2:0] signals are limited to a maximum length of 10 inches for ICH8 and 12 inches for ICH9. For long distances, thick traces are preferred over wide traces. Modify board stackup if necessary to avoid highly resistive traces. The length of each JTXD and JRXD trace must be equal in length to the JKCLK trace or up to 0.5 inches shorter than the JKCLK trace. The JKCLK trace must always be the longest trace in the group. If a length longer than 10 inches (12 inches ICH9) for JTXD[2:0] and JRXD[2:0] is needed, contact your Intel representative for assistance. MDI Differential Pairs Place LCI termination carefully. Design traces for 100 Ω differential impedance (± 20%) Place the at least 1 inch from the integrated magnetics module but less than 4 inches. Place the JTXD[2:0] termination close to the ICH. Place the JRXD[2:0] termination close to the Primary requirement for 10/100/1000 Mb/s Ethernet. Paired 50 Ω traces do not make 100 Ω differential. Check impedance calculator. With closer spacing, fields can follow the surface of the magnetics module or wrap past edge of board, increasing EMI. If the board does not have power and ground planes along the edge, the problem could be worse. Larger spacing increases the insertion loss of the MDI signals and decreases amplitude, which might cause IEEE failures. The optimum location is approximately 1 inch behind the magnetics module. Avoid highly resistive traces (for example, 4 mil traces longer than 4 inches) Make traces symmetrical If trace length is a problem, use thicker board dielectrics to allow wider traces. Thicker copper is even better than wider traces. Traces are 4 mils wide with 8 mils of separation (inside of a pair) for designs with a dielectric thickness of 2.8 mils (nominal). Pairs should be matched at pads, vias and turns. Rules for the autorouter should be carefully established. Asymmetry contributes to impedance mismatch. MDI pairs must not use autorouter. Do not make 90 bends. Bevel corners with turns based on 45 angles Minimize through holes (vias). If using through holes (vias), the budget is two 10 mil finished hole size vias per trace. Keep trace-to-trace length difference within each pair to less than 50 mils. Pair-to-pair trace length does not have to be matched as differences are not critical. Keep differential pairs 30 mils or more away from each other and away from parallel digital traces. This minimizes signal skew and common mode noise. Improves long cable performance. The difference between the length of longest pair and the length of the shortest pair should be approximately 2 inches. A 25% difference in length from the longest pair to the shortest pair is typical. This minimizes crosstalk and noise injection. Guard traces are generally not recommended and can reduce the impedance if done incorrectly. Reference the geometry of the platform design guide. 2

3 MDI Differential Pairs Keep traces at least 0.1 inches away from the board edge. Avoid unused pads and stubs along the traces Route traces on appropriate layers. This reduces EMI. Unused pads and stubs cause impedance discontinuities. Run pairs on different layers as needed to improve routing. Use layers adjacent to ground layers. There must be no splits in the GND planes. When differential signals transition from one board layer to another, place ground vias within 40 mils of the signal vias. If the differential signals transition from a ground referenced layer to a power referenced layer, place a decoupling capacitor on the power and ground within 40 mils of the signal vias. Avoid broadside coupling to traces on other layers. The broadside effect significantly increases the insertion loss and reduces signal quality. Make sure digital signals on adjacent layers cross at 90 angles. Magnetics Module Place MDI termination resistors and capacitors less than 0.25 inches from the Capacitors connected to center taps should be placed very close (less than 0.1 inch recommended) to integrated magnetics module. Deliver 1.8V to the magnetic center tap with a plane. GLCI Interface Design traces for 100 Ω differential impedance (± 20%) Long traces are allowed up to 13 inches, but avoid highly resistive traces. Make traces symmetrical. Improves IEEE performance by reducing reflections. Use symmetrical pads. Minimize any stubs. Placement contributes directly to IEEE performance. Narrow finger-like planes and very wide traces are allowed. If using traces, aim for 100 mils (minimum). Planes are lower inductance and lower resistance than traces and provide better IEEE performance. Paired 50 Ω traces do not make 100 Ω differential. Check impedance calculator. Traces are 4 mils wide with 8 mils of separation (inside of a pair) for designs with a dielectric thickness of 2.8 mils (nominal). For long distances, thick traces are preferred over wide traces. Modify board stackup if necessary to avoid highly resistive traces. Traces should be routed diagonal to the FR4 weave to maintain consistent impedance. If 1 ounce copper is used, minimum trace spacing within each differential pair must be >= 8 mils. GLCI trace lengths can be extended up to 13 inches by limiting the number of vias in the TX and RX paths of the GLCI traces to 4. Try to match the pairs at pads, vias and turns. Establish rules carefully for the autorouter. Asymmetry contributes to impedance mismatch. Do not make 90 bends. Bevel corners with turns based on 45 angles. 3

4 GLCI Interface Minimize through holes (vias). If using through holes (vias), the budget is six 10 mil finished hole size vias on the Rx traces, and 4 on the Tx traces. The Rx side vias must be reduced to 4 inches in order to increase the length of the GLCI buses to 13 inches. Keep traces close together within differential pairs. Keep trace-to-trace length difference within each pair to less than 10 mils. Traces are 4 mils wide with 8 mils of separation (inside of a pair) for designs with a dielectric thickness of 2.8 mils (nominal). If spacing is less than 6 mils, it is almost impossible to achieve >90 Ω differential impedance. Minimizes signal skew and reduces common mode conversion. Keep GLCI differential pairs approximately 15 mils or greater away from each other. The minimum separation is 15 mils for designs with a dielectric thickness of 2.8 mils (nominal). Minimizes crosstalk and noise injection. This includes spacing to other digital traces, I/O ports, board edge, transformers and differential pairs. If using a larger dielectric thickness, keep adjacent traces away by at least 6 times the dielectric thickness. For example, 4.5 mil thick FR4; spacing >= 27 mils. Keep traces greater than 0.1 inch from the board edge. Reduces EMI. Avoid unused pads and stubs along the traces. Use 0 Ω resistors sparingly if needed. Route traces on appropriate layers always reference to GND. Run pairs on different layers as needed to improve routing. Use layers adjacent to ground layers. There must be no splits in the GND planes. When differential signals transition from one board layer to another, place ground vias within 40 mils of the signal vias. If the differential signals transition from a ground referenced layer to a power referenced layer, place a decoupling cap on the power and ground within 40 mils of the signal vias. Avoid broadside coupling to traces on other layers. The broadside effect significantly increases the insertion loss and reduces signal quality. Make sure digital signals on adjacent layers cross at 90 angles. For the GLCI interface, place AC coupling capacitors close to the transmitters. The AC coupling is always at the transmitter on the GLCI interface. Power Supply and Signal Ground Keep the routed length of the CTRL_10 and CTRL_18 signals to the external PNP transistors less than 1 inch. This reduces oscillation and ripple in the power supply. Route the CTRL_10 and CTRL_18 signals as 12 mil wide traces. Keep CTRL_10 and CTRL_18 lines greater than 10 mils away from other signals. Low inductance and low capacitance feedback paths reduce oscillations and ripple in the power supply. This includes spacing to other digital traces, I/O ports, board edge, transformers and differential pairs. 4

5 Power Supply Use planes to deliver power. and Signal Ground Use decoupling and bulk capacitors generously. Verify that the PNP transistors have a 1/2 inch x 1/2 inch thermal relief plane on layer 1. Narrow finger-like planes and very wide traces are allowed. If using traces, aim for 100 mils (minimum). Planes are lower inductance and lower resistance than traces. Place decoupling and bulk capacitors close to the 82566, with some along every side, using short, wide traces and large vias. If power is distributed on traces, bulk capacitors should be used at both ends. The extra copper on layer 1 reduces the Theta-ja of the transistor, which improves the power dissipation. Shape is not important, but surface area is important. Connect the thermal relief to the ground plane with 5 vias to minimize the inductance in the power delivery circuit IVRd: Apply to both the 1.0V and the 1.8V external PNP transistors IVRi: Applies to the 1.8V external PNP transistor. The 1.0V external PNP transistor is not present. Chassis Ground Consider using a separate chassis ground for the LAN connector. Consider placing ground stitching capacitors. If using a discrete magnetics module, provide a separate chassis ground island to ground the shroud of the RJ- 45 connector and to terminate the line side of the magnetics module. This design improves EMI behavior. Split in ground plane should be at least 50 mils wide. Split should run under center of magnetics module. Differential pairs never cross the split. without USB, provide a separate chassis ground island to ground around the RJ- 45 connector. Split in ground plane should be at least 50 mils wide. with USB, do not use a separate chassis ground without USB, place 4-6 pairs of pads for stitching capacitors to bridge the gap from chassis ground to signal ground. Determine exact number and values empirically based on EMI performance. Expect to populate approximately two capacitor sites. with USB, do not use stitching capacitors. LED Circuits Keep LED traces away from sources of noise, for example, high speed digital traces running in parallel. LED traces can carry noise into integrated magnetics modules, RJ-45 connectors, or out to the edge of the board, increasing EMI. 5

6 LED Circuits If using decoupling capacitors on LED lines, place them carefully. Capacitors on LED lines should be placed near the LEDs (typically adjacent to integrated magnetics module). INFORMATION IN THIS DOCUMENT IS PROVIDED IN CONNECTION WITH INTEL PRODUCTS. NO LICENSE, EXPRESS OR IMPLIED, BY ESTOPPEL OR OTHERWISE, TO ANY INTELLECTUAL PROPERTY RIGHTS IS GRANTED BY THIS DOCUMENT. EXCEPT AS PROVIDED IN INTEL'S TERMS AND CONDITIONS OF SALE FOR SUCH PRODUCTS, INTEL ASSUMES NO LIABILITY WHATSOEVER, AND INTEL DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY, RELATING TO SALE AND/OR USE OF INTEL PRODUCTS INCLUDING LIABILITY OR WARRANTIES RELATING TO FITNESS FOR A PARTICULAR PURPOSE, MERCHANTABILITY, OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT. Intel products are not intended for use in medical, life saving, life sustaining applications. Intel may make changes to specifications and product descriptions at any time, without notice. This document contains information on products in the design phase of development. The information here is subject to change without notice. Do not finalize a design with this information. The Gigabit Ethernet Controller may contain design defects or errors known as errata which may cause the product to deviate from published specifications. Current characterized errata are available on request. *Other names and brands may be claimed as the property of others. Copyright Intel Corporation 2004, 2005,